1. Field of the Disclosure
The present application relates to a liquid crystal display device and a fabrication method thereof. More particularly, the present application relates to a liquid crystal display device and a fabrication method thereof that reduce capacitance on a data line and the delay of a data signal.
2. Description of the Related Art
Liquid crystal display (LCD) devices have advantages such as low driving voltage, low power consumption, and portability. Hence, the LCD devices are used in a variety of application fields including notebook computers, monitors, space ships, aircrafts and so on.
The LCD device includes lower and upper substrates and a liquid crystal layer interposed between the two substrates. Such LCD device adjusts light transmittance and displays an image, by controlling molecular alignment of the liquid crystal layer based on application of an electric field.
Depending on how the molecular alignment of the liquid crystal layer is controlled, LCD devices can be classified, for example, into a twisted nematic (TN) display, a vertical alignment (VA) display, an in-plane switching (IPS) display, and a fringe field switching (FFS) display.
In the IPS and FFS devices, both pixel and common electrodes are arranged on a lower substrate. Also, the IPS and FFS devices control the molecular alignment of the liquid crystal layer using an electric field between the pixel electrode and the common electrode.
In detail, the IPS devices generate a lateral electric field between the pixel electrode and the common electrode which are arranged alternately with and parallel to each other, in order to control liquid crystal molecular alignment of the liquid crystal layer. The FFS devices separate the pixel electrode and the common electrode using an insulation layer which is formed between the two electrodes. Also, the FFS devices allow one of the pixel electrode and the common electrode to be formed in a plate shape but also the other to be formed in a finger shape. Such a FFS devices control liquid crystal molecular alignment of the liquid crystal layer using a fringe electric field generated between the two electrodes.
An LCD device of the FFS mode may include a liquid crystal panel configured with a thin film transistor array substrate and a color filter array substrate which face the thin film transistor array substrate. The thin film transistor array substrate and the color filter array substrate can be adhered to each other by a sealant formed between the two substrates.
The thin film transistor array substrate includes the common electrode and pixel electrode formed to have an insulation layer therebetween. The liquid crystal layer is driven by the electric field formed between the common electrode and the pixel electrode. In detail, molecular alignment of the liquid crystal layer is adjusted according to a direction of the electric field which is formed between the common electrode and the pixel electrode.
Also, the thin film transistor array substrate includes gate and data lines that intersect with each other. The gate and data lines define a pixel region, and a thin film transistor is formed at each intersection of the gate and data lines. The thin film transistor is electrically connected to the pixel electrode. Meanwhile, the color filter array substrate includes a black matrix, a color filter layer and an overcoat layer sequentially formed on it.
The common electrode with the plate shape is formed on the entire surface of the thin film transistor array substrate provided with the gate and data lines and the thin film transistor. Also, the common electrode is formed in such a manner as to overlap with the data line. Insulation layers such as a passivation layer, a planarization layer and so on, are formed in an overlap region of the common electrode and the data line. In other words, the insulation layers are interposed between the common electrode and the data line.